1. Field of the Invention
The present invention relates to an electric junction box suitable for use in interconnections with wire harness.
2. Description of the Prior Art
FIG. 1(A) shows an example of prior-art electric junction box A, which includes an upper box cover 1, a lower box cover 2, and a plurality of distributing boards a, b, . . . sandwiched between the upper and lower box covers 1 and 2 one over the other. Each distributing board is composed of an insulating board 3 on which a plurality of bus bars 4 are arranged. Each bus bar is formed with a plurality of angled (vertical) branch tabs 5. For instance, in the case of the second distributing board b, a bus bar 4.sub.1, is formed with three branch tabs 5a, 5b and 5c, in such a way as to constitute an electrode group together with other tabs of the other bus bars. For instance, the tab 5a extends to a connector housing 9; the tab 5b extends to a fuse cavity 10; and the tab 5c extends to a relay cavity 14. Further, in FIG. 1(A), each distributing board is formed with tab insertion holes 6 and intermediate junction terminals 7 having two female portions at both the ends thereof. The upper box cover 1 is provided with a number of fuses 11, relays 12, and circuit breakers 13.
FIG. 1(B) is an internal circuit diagram of the prior-art electric junction box shown in FIG. 1(A). This diagram indicates that a bus bar 4.sub.2 (shown by thick lines) is branched into four tabs 5d, 5e, 5f and 5g on the load side (remote from the fuses), and the tab 5d extends to a lower connector 9A; the tab 5e extends to a lower connector 9B; the tabs 5f and 5g extends to a lower connector 9E. These lower connectors from connector 9A to 9I are connected to a plurality of subharness (not shown) extending from a wire harness via mated connectors 9', respectively.
In the prior-art electric junction box as described above, however, the internal circuits are separated by the bus bar circuits; that is, the bus bars 4 for each distributing board a, b . . . are formed by punching a thin metallic plate and then bending the punched bus bars. In other words, the prior-art junction box is composed of a plurality of different distributing boards. On the other hand, in general the wire harness is divided into a plurality of subharness, in order to simplify manufacturing process and wiring work.
Therefore, when the prior-art junction box is connected to a wire harness provided with subharness, these bus bars 4 (4.sub.1, 4.sub.2, . . . ) formed on each distributing board a, b, . . . must be arranged so as to be mated with the connectors 9 (9A, 9B, . . . ). Therefore, various problems arise in the prior-art junction box constructed by bus bars as follows:
(1) Since each tab 5 must be extended to the lower connector 9A-9I after having passed through each tab insertion hole 6, formed in the distributing board there exists broad wasteful areas where bus bars 4 cannot be arranged on each insulating board 3, so that the degree of freedom of wiring or arranging bus bars on each distributing board is markedly reduced. PA0 (2) Since each bus bar 4 must be arranged so as not to be brought into contact with other bus bars 4 on the same distributing board, the circuit pattern of the bus bars is complicated and specialized according to the kinds of the junction boxes. That is, parts are difficult to be standardized so as to be applicable to various requirements for various degrees of products, for instance to various models of automotive vehicles. PA0 (3) Therefore, it is difficult to modify the internal circuit of the junction box, and therefore many circuits are wastefully used according to the necessity.